Oklahoma’s roofs are built to resist wind more than snow. The ground snow load at Oklahoma City is light enough that it rarely drives a truss design on an ordinary house, wind speed is the number that actually shapes rafters, sheathing and the connections holding a roof to the walls, and whether an ice barrier is required comes down to how cold the winters run rather than how much snow falls. Pull your county’s adopted building code before you order truss drawings, since that document, not this page, is what a plan reviewer checks.
What is the ground snow load in Oklahoma?
The design ground snow load at Oklahoma City is 10 psf under ASCE 7-16, the edition IRC/IBC 2021 makes applicable in most states. That is the figure a permit application, a plan review, and the truss drawings a builder orders all rely on. It is not what a rafter actually carries: 10 psf is the load measured on the ground itself, before the code applies exposure, thermal and slope factors that convert it into a roof value. For an ordinary heated sloped house roof, that conversion works out to roughly 7 psf of roof snow load, lower again on a steep pitch that sheds snow readily rather than holding it.
A handful of jurisdictions are beginning to look toward ASCE 7-22, which maps this same point at 17 psf. That is not more snow and not a sign that a roof built to the older figure is undersized. The 17 psf figure is a strength-level value, built on a 1.0 load factor instead of the 1.6 factor behind the 10 psf number, so the two describe the same location on different bases rather than two measurements of the same thing.
Both figures belong to Oklahoma City specifically. Elevation and local weather patterns shift the ground snow load elsewhere in the state, so a reader outside the Oklahoma City area should ask their local building department for the value that applies at their own address rather than assume this one travels unchanged.
How much snow can a roof hold in Oklahoma?
There is no single number that answers this, because the answer depends on the roof’s shape, its pitch, and what the snow has turned into by the time it piles up. The 7 psf figure derived from Oklahoma City’s ground snow load describes an ordinary, evenly loaded roof under uniform snow, and real snow rarely sits that evenly.
Drift is where roofs actually fail
Wind moves snow off a windward slope and piles it against a taller wall, below a dormer, in a roof valley, or onto a lower roof beside a taller section of the same house. A drift can load a small section of roof several times over what the uniform, ground-derived figure suggests, even while the average snowfall across the whole roof looks unremarkable. This is the mechanism that causes most snow-related roof failures, far more than a heavy but even blanket of snow ever does.
Weight also changes as snow ages. Fresh, dry snow runs roughly 5 to 7 pounds per square foot for every foot of depth. Settled or wet snow packs down to two to three times that weight for the same depth, and a layer of ice formed from melt-and-refreeze adds more still. A foot of snow sitting on a roof in January, still light and cold, is a different load than a foot that has partly melted and refrozen weeks later.
| Snow condition | Approximate weight per sq ft per foot of depth | Where it forms |
|---|---|---|
| Fresh, dry snow | 5-7 lb | New snowfall, cold and light |
| Settled or wet snow | 2-3x fresh snow | Snow that has sat for days or absorbed melt |
| Ice layer | Heavier again | Melt-and-refreeze at eaves or in shaded valleys |
Watch for the signs that a roof is carrying more than it should: interior doors that suddenly stop closing, new cracks running across ceiling drywall, or a ridge line that has begun to sag instead of running straight. Any of those calls for a licensed engineer or the local building department, not a guess. If snow needs to come off a roof, rake it from the ground with a roof rake rather than climbing onto a roof that is already carrying an unknown load. None of this tells an individual reader whether their own roof is adequate. That answer sits with the truss drawings on file for the house and, where those are not available, with an engineer who can look at the actual framing.
What wind speed must a roof withstand in Oklahoma?
The basic design wind speed at Oklahoma City is 109 mph under ASCE 7-16, the edition IRC/IBC 2021 makes applicable in most states, for Risk Category II buildings, which covers ordinary houses. That figure is a 3-second gust measured at 33 feet in open, Exposure C terrain, not a sustained wind and not the number a weather forecast reports. A hurricane’s headline wind speed and this design gust are not measured the same way, so comparing the two directly leads nowhere useful. ASCE 7-22 maps the same location at the same 109 mph, so the coming edition change does not shift this particular figure.
Risk Category II covers ordinary single-family houses and most commercial buildings. Category III and IV structures, such as hospitals or emergency shelters, are designed to a higher wind speed at the same location, because they need to keep functioning after a storm that would just as easily strip shingles off a house.
That wind speed is what a roof’s shingle wind rating, nailing pattern, sheathing fastening, and the uplift connections between the roof framing and the walls are all sized against. Roofs rarely fail in the middle of a field of shingles. They fail at the edges: rakes, eaves, ridges and hips concentrate uplift pressure far above what the same wind produces over an open expanse of roof, which is why nailing schedules and edge metal get more attention there than anywhere else.
The 109 mph figure applies at Oklahoma City specifically. Wind speed on the design maps varies with location and exposure elsewhere in the state, so a reader outside the Oklahoma City area should confirm the mapped value for their own address with their local building department rather than assume this number travels unchanged. As with the snow figure, this describes a design requirement, not a verdict on any particular roof. Whether a given roof was built to meet it is a question for the permit record and, where that is not available, for a licensed engineer or the building department that issued the original permit.
Does Oklahoma require an ice barrier under the shingles?
An ice barrier is a self-adhering waterproof membrane installed under the shingles, run from the edge of the eave up the roof slope far enough to clear the inside face of the exterior wall. Its job is not to stop snow from accumulating. It is there to stop water from an ice dam from working backward under the shingles and reaching the deck once the dam has already formed.
What actually causes the dam
Ice dams form for a specific reason, and it has almost nothing to do with how much snow falls. Heat escaping from the living space into the attic warms the underside of the roof deck near the ridge, melting the snow sitting above it. That meltwater runs down the slope until it reaches the cold overhang beyond the heated wall line, where it refreezes into a ridge of ice. The next batch of meltwater backs up behind that ridge instead of draining off the eave, and if it finds a way under the shingles it reaches the deck and the ceiling below.
Oklahoma City’s winters are not the harshest in the country. NOAA’s 1991-2020 climate normals put the mean daily minimum for the coldest month at 27.0°F. That is cold enough for repeated freeze-thaw cycles at the eaves during a cold snap with snow already on the roof, but it is a milder baseline than the states where ice-damming shows up almost every winter. Whether an ice barrier is required on a given roof, and where it must start and stop, is a question for the Oklahoma Residential Code, based on the 2018 International Residential Code and administered locally under the Oklahoma Uniform Building Code Commission. That code sets a statewide minimum that a city or county may exceed, and it is scheduled to move to the 2024 International Residential Code edition on September 14, 2026, so a project reviewed on either side of that date should confirm which edition applies to its permit.
A membrane alone does not stop a dam from forming in the first place. That takes air sealing and attic insulation sufficient to keep the underside of the roof deck close to outdoor temperature, so the snow sitting on it does not melt from below. A reader who installs an ice barrier and does nothing about attic heat loss has bought protection for the deck, not a cure for the dam itself, and the same warm-attic problem will keep showing up at the eaves every cold winter.
What roofing material suits Oklahoma best?
Oklahoma’s own numbers point toward a roof built primarily for wind resistance, with snow load a secondary concern except where drift concentrates weight. The roughly 7 psf ordinary roof snow load derived from Oklahoma City’s ground figure is light by national standards, while the 109 mph basic wind speed is a real design load that shapes fastening and connections across the state, not just near Oklahoma City.
Architectural asphalt shingles remain the most common choice, and in wind-driven Oklahoma the number that matters most is the shingle’s own wind rating combined with the nailing pattern actually used on the roof. A shingle rated for a high wind speed performs only as well as its weakest connection: fastening and underlayment govern more than the shingle itself once wind, rather than snow, is the load deciding the outcome. That point holds across roofing generally, a subject covered in more depth on our roofing guide.
Standing-seam metal sheds snow efficiently because of its smooth, low-friction surface, an advantage where snow load is the binding concern and a liability where a roof discharges a slab of snow directly onto a walkway, a doorway or a driveway below. Where metal is chosen for its snow-shedding behavior, the discharge path needs to be part of the design, not something discovered the first time a slide happens.
Slate and concrete tile add their own dead weight to whatever snow load the structure already carries, a bigger factor in states with heavy ground snow loads than in most of Oklahoma, but it still has to be accounted for structurally rather than assumed away because the ground snow figure here is modest. The 2021 International Energy Conservation Code splits Oklahoma’s 77 counties across zone 3A (59 counties), zone 4A (15 counties) and zone 4B (3 counties), which shapes attic insulation and ventilation requirements more than it shapes the choice of roofing surface itself.
States with different combinations of ground snow load and wind speed reach different conclusions entirely, which is why the same worksheet applied to roof snow load and wind speed rules in North Carolina or to roof snow load and wind speed rules in Idaho produces a different answer, and why a roofing decision has to start from the local design figures rather than a generic recommendation.